1. Field of Invention
The invention relates to a mounting method of dental cast and, in particular, to a mounting method of dental cast with sensing technology assistance.
2. Related Art
Clinically, there are many patients having special maxillofacial ratios or incorrect occlusal relationships between upper and lower jaws. Such a kind of abnormally growth problem often accompanies with the facial asymmetry, the mandibular prognathism, the mandible retrusion or the poor occlusal condition on the organization structure. Regarding the life, the patient tends to encounter the stoppages, such as the pronunciation difficulties, the chewing digestive diseases, the lack of confidence, or even the other's discrimination and the people's strange looks.
Orthodontics is one of the developed therapeutic methods to solve the above problems. In general, during the first consultation, it is necessary to collect the growing record of the patient, make the dental plaster model, inspect the mouth by X-ray, and take the photos of the face and teeth for drafting the proper treatment plan. Then, the removable and fixed orthodontic treatments are applied in sequence according to the treatment plan. In this procedure, the drafted treatment plan is one of the factors of the orthodontics result. Of course, if the drafted treatment plan can not exactly indicate the occlusal relationship of the patient or have some errors, the following orthodontics procedure can be sufficiently affected. Regarding to the above problems, when the situation of the patient is too worse to be treated by orthodontics, it still exists another general and effective treatment, which is to correct the spatial positions of the maxilla and mandible through the surgery and to reconstruct the good occlusal relationship. This kind of surgery is typically referred to as an orthognathic surgery. Similarly, because the object of the orthognathic surgery is to correct the upper facial structure of the jaw, such as the facial asymmetry, the facial harmonious proportion or the like, as well as the growth problem, or to correct the skeleton structure change, which cannot be easily or cannot be completed using braces. So, the detailed preoperative diagnosis has to be made such that the orthognathic surgery planning can be established in connection with the actual situation of the patient's maxillofacial skeleton structure, and the jawbone can be indeed moved to the proper position. Thus, this is referred to as the “orthognathic surgical planning”, “orthognathic planning” or “orthognathic surgery planning”, the quality of which significantly affects the quality of the surgical behavior.
The orthognathic plan is drafted based on the good symmetry of the dentition and facial jawbone, so that the oral surgery plan can be performed according to the facial characteristics and the occlusal relationship. However, the drafting of the orthognathic plan still encounters many important issues. As mentioned above, either the orthodontics or the orthognathic surgery needs an additional device for transferring the relative relationship between the dentitions, maxilla and mandible, so that the operator or doctor is able to draft a precise surgery plan for the patient. The conventional method is to use a face bow to transfer the relative relationship to an articulator, and then utilize the cephalometric analysis to draft the orthodontic plan or orthognathic plan.
The articulator can match the jawbone characteristics of the patient, such as condyle and Frankfurt horizontal plane (FH plane). The face bow can record the relative relationship of the maxilla and mandible, so that the dental cast of the patient can be precisely fixed on the articulator. Thus, the articulator can exactly reproduce the relationship of jawbone of the patient. This action of positioning and fixing the dental cast on the articulator by the face bow is a mounting step.
However, after the long term experience, it has been proved that the incorrect record of the face bow always results the mounting error, which is one of the major factors causing the unsatisfied orthodontic result with respect to the desired orthodontic plan. Accordingly, various kinds of modified face bows are disclosed to improve the existing problem, but they still have the following drawbacks. First, the included angle between the FH plane and the occlusive surface may be mismatch with each other. This is because the FH plane may not be kept in horizontal when mounting the palate dental cast on the conventional articulator even in the same case in different times. Unfortunately, the mounting of the face bow never considers this undesired event. Second, different postures of the patient may result in different positions of the mandible. According to some researches, when the patient changes his/her posture, such as standing or sitting, the position of mandible can not stay at a fixed position, resulting in undesired error. Third, since the position of the rotation axis of lower jaw, the condyle axis, is a predicted result average measuring from skin, it is possible to cause the error on the third reference point.
Because the convention method to mount the dental cast of the patient on the articulator by the face bow still has some drawbacks, the relative relationship of the dental cast and the articulator may not exactly represent the actual situation. This may increase the mistakes during the orthodontics or orthognathic surgery, or limit the effect of the treatment. Therefore, it is an important subject of the present invention to provide a novel mounting method that can be performed without using the face bow so as to decrease the possible mechanical errors. Moreover, the mounting method of the invention can provide, for example, the 3D visualization and/or quantified data to guide or assist the operator/doctor, thereby decreasing the blind spots of the mounting process so as to exactly transfer the situation of the facial jawbone to the articulator, so that the goal of increasing the success rate of orthodontics and orthognathic surgery can be achieved.